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higher temperature (170°) of the {3 compound. /3-Naphthol and
its derivatives are used for the preparation of azo-colours (see
Reaction 6, p. 163), and for that of/3-naphthylamine. The latter
is obtained by the action of ammonia under pressure on #-

C10H7OH + NH3 = C10H7NH2 + H2O.

This reaction is resorted to for the reason that naphthalene
forms only the a-nitro-compound with nitric acid. The method,
similar to that used for preparing' aniline from nitrobenzene,
cannot, therefore, be employed for the production of #-naphthyl-
amine. a-Naphthol is mainly used for the manufacture of
yellow and orange colours (Marti us and naphthol yellow) by
the action of nitric acid, and are similar in constitution to picric
acid (see Prep. 107).

The naphthols differ from the phenols of the benzene series
in forming ethers after the manner of aliphatic alcohols, viz., by
the action of sulphuric acid on a mixture of the naphthol and the
alcohol, which the other phenols do not,

C10H7OH -f CHaOH = C10H7OCH, -I- H3O

Naphthyl methyl ether.


Anthraquinone.— The constitution of anthraqninone is
derived from various syntheses, such as the action of zinc dust
on a mixture of phthalyl chloride and benzene, or by heating
benzoyl benzoic acid with PL>O5,

,COCl                         /OX

I4 -I- 2HCI




= QH/       ,v



:«ir4 -i-

Unlike benzoquinone, it is not reduced by sulphur dioxide
(see Prep. 85, p. 193). Heated with HI or 'zinc dust it is con-
verted into anthracene.
Alizarin. — The first synthesis of alizarin is due to Graebe
and Liebermann (1868). The present method was discovered
simultaneously by these chemists and by Perkin. By the action